This invention relates to display systems for digital oscilloscopes in general, and in particurlar to a display system including an interpolator for interpolating between stored waveform samples and providing additional samples at the interpolated values.
In prior art digital display systems, only the stored waveform samples are utilized in reconstructing the stored waveform for display. Typically, many samples per cycle of an input signal are taken so that a reasonable facsimile of the input waveform may later be constructed. If the waveform is reproduced as a dot display, a minimum of about 25 samples per cycle are generally required to produce a recognizable sine wave dot display. If a vector generator is utilized to essentially connect the dots, a minimum of about 10 samples per cycle are needed to provide a displayable waveform having no appreciable distortion. Thus the usable bandwidth of a digital oscilloscope is limited by the sample density per cycle of input signal.
Expensive and sophisticated digital oscilloscopes employ high-speed sampling and analog-to-digital converter systems coupled with memory devices capable of receiving the waveform data; however, even for these oscilloscopes, the frequency of the input signal can reach a point where the sampling density is reduced to a point that an unintelligible display is produced.